This could well be remembered as a watershed week in media coverage of British politics, when John Prescott's career was brought crashing down by a self-styled internet 'anarcho-capitalist' named Paul Staines.

Staines - aka 'Guido Fawkes' - is the most in-your-face of Britain's new tribe of political bloggers. Alongside Iain Dale, a former Tory parliamentary candidate who helped to run David Davis's bid for the party leadership, he has led the way over the past week in churning out a battery of allegations about Prescott's political and private life.

The effect has been extraordinary. By the week's end, the BBC's political editor, Nick Robinson, was trading cyber-jibes with the blogging duo. Prescott's biographer Colin Brown wrote darkly in the Independent of a Tory-inspired online plot to bring down the deputy PM. And if there were any doubt that British political blogs had come of age, it was dispelled on two of the old-media preserves of political discourse: the BBC's Newsnight and Radio 4's Today Programme

Newsnight interviewed Dale about the Prezza blogs in mid-week. The next morning, Today's John Humphrys - taking his cue from allegations on Guido's blog - grilled Prescott about claims of further extramarital affairs.

'Guido' could barely contain his online glee. 'John Humphrys did what he is paid to do this morning.' He was particularly trenchant in countering Prezza's allegations that he was part of some 'Tory' smear campaign. 'Guido has some news for Prescott's office,' Staines blogged. 'It is more of a Brownite, fingerprint-free "let him hang out to dry campaign". If anything, the Tories would prefer him rotting in office.'

Blog is short for weblog, and there are currently around 50 million in cyberspace. Many have absolutely nothing to do with politics. Some are detailed accounts of making coffee, watching TV or just marking time, and most could benefit from a spellchecker. But, in a trend that began in the United States and has now erupted here with a vengeance, a wide range of political bloggers have begun to make their mark.

In the US, the Connecticut Senator and former vice-presidential candidate Joe Lieberman has seen his yawning lead in opinion polls suddenly slashed in the run-up to November's elections by support from anti-war political bloggers for his little-known Republican challenger.

In Britain, the first major invasion by bloggers into mainstream politics came in the last general election campaign. It was 'Guido' who propelled a series of Labour election posters depicting Michael Howard as the Jewish stereotype Fagin into the mainstream media, thereby transforming his site from an internet backwater that received 60 hits a day into a prominent resource that now receives around 150,000 hits a day.

When Howard lost the election and proposed changing the rules on electing party leaders to take the final say away from ordinary party members, the conservativehome.com website launched an online campaign to galvanise grassroots opposition.

Conservativehome, inspired and run by former Iain Duncan Smith central-office aide Tim Montgomerie, is now the leading platform for conservative bloggery. Dale's breakthrough came more recently, when he singlehandedly inflated national coverage of the auction of a copy of the Hutton Report autographed by Cherie Blair.

In recent months indications have been growing that Britain's political and media establishment is waking up to the political bloggers. The Guardian recently became the first national newspaper to set up a blogsite, Comment is free. Writers from virtually all other British broadsheets, and the BBC, now have their own blogs. Dozens of MPs, with the Lib Dems' Lynne Featherstone as a trailblazer, have joined in - although to judge from David Miliband's blogsite, they have yet to break the habit of communication by press release. The same goes for Downing Street: a recent Podcast by Eddie Izzard of his close look at Tony Blair's trip to a Euro-summit was proof that even comedians can be both unfunny and uninteresting.

The new-look Tories seem intent on setting the cyber-pace in British politics. Earlier this year they dispatched Montgomerie to the US to take a closer look at Republican politicians' increasingly sophisticated use of the internet. And conservativehome recently revealed that Central Office has hired a former Google employee and Oxford graduate named Sam Roake to rethink the Tories' cyber-strategy. Working under Cameron's top aide Steve Hilton, he is responsible for 'harnessing community websites and the blogosphere', according to conservativehome.

On Friday the Hansard Society announced it would be holding a seminar this month on whether Westminster is 'ready for the age of participatory media' - a fancy term for the internet bloggers, chatters and 'community' sites. 'Should the Speaker register with FaceBook?' the Society asked. 'Is Google-Video the best place to webcast select committee meetings?'

However, the Westminster village was preoccupied with more urgent cyber-questions last week. Robinson's blog put it best, describing the Prescott story as 'an example of some blogs trying to make the political weather.

'First, they demand to know why the mainstream media - and in particular, the BBC - are not covering an alleged "scandal". Then they report unsubstantiated allegations which have been denied by those involved, which some newspapers then report as second-hand news.'

'Let's be clear,' he added. 'This isn't because they are better journalists, free from censorship. They often have a political agenda.'

Dale said yesterday his 'agenda' was aimed at opening the confines of Westminster political discourse. 'Guido' has told friends that his motivation is that he 'genuinely despises politicians blatantly lying to us', adding that far from having a 'Tory' agenda, 'after a few drinks, I think anarcho-capitalism is the best way of organising humanity'.

Asked by The Observer why he thought his blog had generated such heated criticism, he said: 'The main problem for everybody for me is that (a) I don't want a career in politics (b) I don't want a career in journalism (c) I have resources and ability, and (d) I don't give a flying fuck what you think.'

Interestingly, by the end of the week, Robinson had retreated slightly from the fray. 'I seemed to stir up a hornet's nest by pointing out that certain blogs are running unsubstantiated and politically motivated allegations about the Deputy Prime Minister's private life,' he blogged.

'I was not attacking them. I do read them. I enjoy them but there is, rightly, a difference and a distance between what they do and what I do.' If the saga of John Prescott is any indication, that distance may be inexorably shrinking.

Politicobloggery: a taster's guide to six of the best

Guido Fawkes

What it says on the cover: 'People should not be afraid of their government. Governments should be afraid of their people.' Tone: in your face. Political outlook: an equal-opportunity stirrer.

What it says on the cover: 'Liberty, if it means anything, is the right to tell people what they don't want to hear.' Tone: serious but readable, not for the political surface-skater. Political outlook: iconoclastic left-of-centre.

What it says on the cover: melaniephillips.com (this is, after all, the most no-nonsense, frill-less of our national newspaper columnists.) Tone: non-smalltalking, argumentative, serious - particularly on radical Islam, family values, etc. Political outlook: firmly on the right.

What it says on the cover: 'This blog is my attempt to help bridge the growing and potentially dangerous gap between politicians and the public. It will show what I'm doing, what I'm thinking about, and what I've read, heard or seen which has sparked interest or influenced my ideas. My focus will be on my ministerial priorities. This supplements the existing ways of doing day-to-day business with me and my department.' (After all, David may be the best and the brightest of Labour's crop of young stars, but remember that he is also a government minister down to his fingertips.) Tone: press release-ease. Political outlook: New Labour.